A 59 years old woman with a ' Malign ' peritoneal fluid underwent total abdominal hysterectomy, bila-teral salpingooophorectomy with an initial diagnosis of ovarian tumour. A serous carcinoma limited to an endometrial polyp was seen in histopathologic examination.

Carcinoma development in an endometrial polyp is a rare event and serous carcinoma has a poorer prognose among them. Because of the cooccurrence of an endometrial polyp with serous carcinoma, these two conditions were discussed with the review of the literature.